The present invention relates to electrical feedthroughs and more particularly to feedthroughs which include electrical contact means for making electrical connections to pressure transducers used for sensing a pressure or a differential pressure. More specifically this invention relates to an electrical feedthrough and contact means for pressure transducers of the capacitive type.
Capacitive type pressure transducers in which the present invention is useful include the type which utilize a silicon diaphragm and silicon plates both made from highly doped silicon. The plates may be anodically bonded to the diaphragm with material removed from the plates and diaphragm to provide contact areas which are all accessable from one side. In such transducers it is necessary to provide a means for connecting the elements of the transducer to the circuit board which carries the associated circuitry. This circuit board is usually located in the housing of the transducer assembly in a region which is not subjected to the high line pressures to which the transducer is exposed. It is thus necessary to electrically connect the transducer to the circuit board through a pressure sealing arrangement or bulkhead.
Certain prior art transducer assemblies have used leaf type springs to make contact between the transducer and the circuit board others have used direct soldered wiring connections. These arrangements have made it difficult to minimize the volume of silicone oil contained in the cavities of the transducer, for they both take up an excessive amount of space by the very nature of their construction. It should be recognized that it is very important to minimize the volume of silicone oil or other fluid medium in the cavities of the transducer assembly in order to minimize the effect of pressure changes and temperature changes on that fluid and hence on the transducer output.
It is an object of the present invention to provide a feedthrough for a pressure transducer which is simple, inexpensive to manufacture and easy to assemble.
It is also an object of this invention to provide a feedthrough for pressure transducers which takes up only a minimum space in the cavities of the transducer.